Chicago is a big dot on the architectural map because of its pre-eminent role in the invention of the office skyscraper, a development that transformed the skylines of cities worldwide. But thanks to the Great Recession, it's been seven years since a major downtown office building opened here. Now we have a new one, and its exuberant curves take full advantage of its prominent riverfront site.

River Point, as the 52-story office building at 444 W. Lake St. is known, has a clear kinship with 333 W. Wacker Drive, the great 1983 high-rise with curving green glass walls that exquisitely mark a bend in the Chicago River. Though River Point doesn't meet the high bar of its neighbor across the river, it enhances the waterfront with its sleekly sculpted form and an inviting 1.5-acre plaza.

Good modernism, this tower shows, is not incompatible with the making of good cities.

Designed by New Haven, Conn., architects Pickard Chilton and developed by the Chicago office of Houston-based Hines, the $500 million project transforms a challenging site that marred the riverfront with exposed railroad tracks and a surface parking lot. A lot of engineering acrobatics, devised by Seattle-based structural engineers Magnusson Klemencic Associates, went into this significant shift.

The plaza is essentially a land bridge, supported by concrete beams that span tracks on which passenger trains still run. To avoid hitting the tracks, some of the office building's steel columns lean inward. In addition, some of the tower's caissons had to be shifted so they didn't pierce the Chicago Transit Authority's Blue Line tunnel 60 feet below the site. Anybody who thinks architecture is all style, no structure, should pay a visit to 444 W. Lake.

Phil Velasquez / Chicago Tribune

The new River Point building at 444 W. Lake St. on Dec. 7, 2016.

The new River Point building at 444 W. Lake St. on Dec. 7, 2016.

(Phil Velasquez / Chicago Tribune)

Which is not to deny that there's style here — or that River Point departs from the old Chicago norm of boldly expressing the underlying steel frame. It doesn't. But there is a structural rationale for the building's most distinctive feature: the tall parabolic arch at its base, which is echoed (without structural rationale) by a shallower arch at the tower's top.

In essence, the architects dramatized the base with an angled glass wall that follows the tilt of the leaning columns. Slice a plane into a curving facade like this one and you get a parabolic arch. Even if that geometry is lost on you, the aesthetic effect should be apparent: A swoopy exuberance that, for some, will evoke the Space Age optimism of the 1960s and, for others, will summon the dynamic digital-age designs that were all the rage before the 2008 crash.

As it turns out, River Point was designed before the recession. Hines was ready to build it but had to hold off until the economy recovered.

The site, a right triangle at the confluence of the Chicago River's north, south and main branches, invites a memorable statement. And with some exceptions, that's what the designers have delivered.

From afar, the tower's curves offer a rare, if somewhat bland, departure from the right-angled lockstep of the skyline. At closer range, you might notice how the tower joins with 333 to form a double-curved gateway to the river's south branch.

Phil Velasquez / Chicago Tribune

The new River Point building at 444 W. Lake St. on Dec. 7, 2016.

The new River Point building at 444 W. Lake St. on Dec. 7, 2016.

(Phil Velasquez / Chicago Tribune)

From closer still, you can take in the visual pleasure of the tower's angled glass wall, which is framed by the parabolic arch and composed of super-transparent, low-iron glass at lobby level and conventional glass above. In a wonderful and unanticipated touch, the angle creates a mirror effect, reflecting the river's shimmering water and boats skimming across it. Even the tower's chief designers, Pickard Chilton's Anthony Markese and Jon Pickard, admit they didn't expect that.

The parabolic arch is more bulky and rib-like than it appeared in renderings, a shortcoming largely due to the fact that it must also serve as a gutter that funnels rainwater away from the building's main entrance. Such are the nitty-gritty conflicts of form and function. Once internal lighting is installed and the top and bottom arches glow from within, River Point may achieve its full aesthetic potential.

The tower's urban design is also a success, with the exception of a hard-edged precast concrete wall that lines a new riverwalk beneath its plaza. The wall is there because Amtrak required that the plaza be high above river level, allowing clearance for its trains. The project's landscape architect, Houston's James Burnett, has tried to camouflage the wall with pear trees, grasses and ivy. They are essentially a fig leaf.

Even so, River Point's plaza offers much-needed open space and spectacular views of the skyscraper-lined waterfront. The open space is tailor-made, with a curving pedestrian path that echoes the facade's parabolic arch. Ample seating encourages people to use the space, as does a ramp that leads to the plaza from Lake Street. While the public is helping pay for this public space, via a city subsidy that covered a significant chunk of the plaza's cost, that was money well spent considering the alternative — the maintenance of a waterfront eyesore that would have undercut the city's drive to engage and beautify the river.

Phil Velasquez / Chicago Tribune

The new River Point building at 444 W. Lake St. on Dec. 7, 2016.

The new River Point building at 444 W. Lake St. on Dec. 7, 2016.

(Phil Velasquez / Chicago Tribune)

Significantly, the tower's distinctive form has not come at the expense of function. A recent tour of several office floors revealed amply-sized column-free floors and striking views created by floor-to-ceiling windows. The developers took care to shield tenants from the racket of passing "L" trains on Lake Street with a triple-layered glass facade. The main lobby, at plaza level, is enriched by travertine walls, a subtly lit scalloped ceiling and a sense of expansiveness created by huge sheets of angled low-iron glass.

The care and cost lavished on the lobby speak to the aesthetic ambition of this project — a welcome shift from the bare-boned, vanilla apartment buildings that have been taking up space in Chicago's skyline but adding little oomph. One waits with anticipation and trepidation to see whether River Point and its neighbors — the soon-to-be-open 150 North Riverside office tower and planned skyscrapers at Wolf Point — create a distinguished high-rise cluster that's more than the sum of individual parts.